Personal information management (PIM) software is widely used today for recording appointments and other calendar events. PIM software is used on both desktop computers and handheld computing devices. Often, the PIM database on one computer will be synchronized with a PIM database on another computer. Some PIM software includes enterprise synchronizing and scheduling capabilities that synchronize PIM databases for users across an enterprise, or that schedule meetings for multiple participants in the enterprise.
Some PIM software, typically software intended for desktop use, represents the time of appointments in universal time (UTC), which is equivalent to Greenwich Mean Time (GMT). Microsoft Outlook, for example, makes all time entries into its PIM database in universal time (UTC). The actual time that a user sees varies with the time zone setting of the user's software. This arrangement has the advantage that when a user changes time zones (e.g., as a consequence of traveling), his appointments can readily be adjusted to appear in the local time of that time zone merely by entering the new time zone. Also, when PIM databases across an enterprise are synchronized, or appointments scheduled using scheduling software, the different time zones of users in the enterprise are automatically taken into account.
Other PIM software, e.g., the Palm OS, a very widely used PIM software for handheld devices, represents appointments in local time. No provision is made for time zones. As long as the user does not move between time zones, and only synchronizes with another PIM database in the same time zone (e.g., between his desktop and handheld), this limitation is not a practical problem. The latest version of the Palm OS (Version 4.0) has added a limited time-zone capability that allows a user to change his time zone, but making such a change has no effect on appointments, which remain at the local time at which they were first entered.